This invention generally relates to medical devices, and particularly to intraluminal catheters.
In percutaneous transluminal coronary angioplasty (PTCA) procedures, a guiding catheter is advanced until the distal tip of the guiding catheter is seated in the ostium of a desired coronary artery. A guidewire, positioned within an inner lumen of a dilatation catheter, is first advanced out of the distal end of the guiding catheter into the patient""s coronary artery until the distal end of the guidewire crosses a lesion to be dilated. Then the dilatation catheter having an inflatable balloon on the distal portion thereof is advanced into the patient""s coronary anatomy, over the previously introduced guidewire, until the balloon of the dilatation catheter is properly positioned across the lesion.
Once properly positioned, the dilatation balloon is inflated with liquid one or more times to a predetermined size at relatively high pressures (e.g. greater than 8 atmospheres) so that the stenosis is compressed against the arterial wall and the wall expanded to open up the passageway. Generally, the inflated diameter of the balloon is approximately the same diameter as the native diameter of the body lumen being dilated so as to complete the dilatation but not overexpand the artery wall. Substantial, uncontrolled expansion of the balloon against the vessel wall can cause trauma to the vessel wall. After the balloon is finally deflated, blood flow resumes through the dilated artery and the dilatation catheter can be removed therefrom.
In such angioplasty procedures, there may be restenosis of the artery, i.e. reformation of the arterial blockage, which necessitates either another angioplasty procedure, or some other method of repairing or strengthening the dilated area. To reduce the restenosis rate and to strengthen the dilated area, physicians frequently implant an intravascular prosthesis, generally called a stent, inside the artery at the site of the lesion. Stents are usually delivered to a desired location within a coronary artery in a contracted condition on a balloon of a catheter which is similar in many respects to a balloon angioplasty catheter, and expanded to a larger diameter by expansion of the balloon. The balloon is deflated to remove the catheter and the stent left in place within the artery at the site of the dilated lesion.
Catheters designed for intravascular procedures such as angioplasty have a number of design considerations. Such catheters must be able to transmit force along the length of the catheter shaft so that the catheter can be pushed through the patient""s vasculature. However, the catheter shaft must also have sufficient flexibility to allow the catheter to track over a guidewire through tortuous vasculature as well as crossing stenosed portions of the vascular anatomy.
Prior art intravascular catheters have commonly included a soft distal tip to prevent or minimize injury to the vessel during advancement of the catheter therein. One difficulty has been forming a connection between the soft tip and the catheter which is sufficiently strong to prevent disengagement of the soft tip or kinking at the junction between the soft tip and catheter shaft. Additionally, it is necessary to balance the strength of the connection between the soft tip and the catheter shaft with the need to minimize the stiffness of the distal end of the catheter. Minimizing the stiffness of the distal end of the catheter results in improved maneuverability of the catheter.
Accordingly, it would be a significant advance to provide a catheter with a soft tip having improved performance. This invention satisfies these and other needs.
The present invention is directed to balloon catheter with improved maneuverability. The catheter includes an elongated catheter shaft having a proximal end, a distal end, proximal and distal shaft sections. A guidewire receiving lumen extends along at least a portion of the catheter shaft to a port of the distal end of the catheter shaft. An inflation lumen extends along at least a portion of the catheter shaft terminating at a point proximal to the distal end of the catheter shaft.
The catheter further includes a tip member on the distal end of the catheter with a proximal end of the tip member spaced distally apart from the distal end of the catheter shaft. A lumen of the tip member is in fluid communication with the catheter shaft guidewire receiving lumen.
An inflatable member, such as a balloon, with proximal and distal ends and an inflatable interior is disposed on the distal section of the catheter shaft. The interior of the balloon is in fluid communication with the inflation lumen. The balloon further includes a distal shaft section adjacent to the balloon distal end with a distally tapered portion. The distal end of the balloon is sealingly secured to the proximal end of the tip member and a portion of the catheter shaft. The distal shaft section tapers distally and forms a tapered distal end with an interior surface defining a portion of the guidewire receiving lumen.
In one embodiment for a method of forming the catheter described above, a catheter assembly is provided which includes a catheter shaft having proximal and distant ends, and a balloon having proximal and distal ends with an inflatable interior and a distal shaft section with an interior surface. A tip member with proximal and distal ends, and a mandrel with proximal and distal ends and a tapered distal portion, are also provided.
The distal end of the catheter shaft is positioned within the interior of the balloon distal shaft section terminating at a point proximal to the balloon distal end. The proximal end of the tip member is positioned adjacent the balloon distal end such that it is distally spaced apart from the catheter shaft distal end. The tapered distal portion of the mandrel is positioned within the interior of the balloon distal shaft section and the tapered distal portion of the mandrel is aligned with the distal end of the balloon distal shaft.
Energy is applied to at least a portion of the balloon distal shaft, bonding such that at least a portion of the balloon distal shaft is bonded to the catheter shaft and at least a portion of the balloon distal shaft section is bonded to the tip member. A distal tip portion of the catheter is formed such that at least a portion of the interior surface of the balloon distal balloon section fluidically connects the catheter shaft and the tip member. Unless stated otherwise, the order in which the steps of the process of making are carried out, are not intended to be limited to the order described.
These and other advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying exemplary drawings.